Ideal Forge Wall Thickness

J

John Frankl

Joined
Oct 16, 2001
Messages
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Hello All,

I have a couple of great forges, but they are made from drums of various sizes. This makes it hard to weld work rests, burner holders, etc. to the body of the forge.

What do all of you feel is an ideal thickness --or a min. and max.--for a forge wall, assuming one wants to weld attachments, rests, etc. directly to it?

Thanks,

John
 
As thick or as thin as you can weld i guess, your insulation should keep the shell from overheating, so i wouldn't think thin would be a problem except for welding to or being to thin to keep it's shape, my forge body is 3/8 thick which is way overkill, but it's all i could come by, welding to it was easy but it weighs a ton,
what kind of welding are you doing?
 
Thanks. That's my point: I know I can weld to 3/8" but I want something under 200 lbs:). What I have now is fine for keeping its shape, but I can't weld on work rests, burner attachments, etc.

John
 
Hi John, See if you can track down some schedule 10 pipe, it's got a wall thickness of 0.148" to 0.180" for 8" diameter and 12" diameter respectively. That's plenty rigid enough to weld to and feel good about it. Schedule 5 is 0.109" and 0.165", respectively, but it's much harder to find...

:)

-Darren

edited to add: Schedule 10 8" diameter pipe weighs in at about 13.5 pounds per foot while schedule 10 12" diameter pipe weighs in at about 24 pounds per foot.
 
Thanks Darren.

I'm having to have some sheet rolled into a pipe because everything here is way too thick. I'm dealing in millimeters so I'll convert the 0.180" figure and go from there. Thanks a bunch,

John
 
John,

I do not weld anything to my forge body. I do use 10ga .110 inch, rolled to spec but I weld all of my holders and rests etc to the stand. This way I can have one forge working and another in the process of being re-built. I don't lose time when the liner wears out. Not that I rebuild all of the time. Also it makes the forge a bit more portable. I can just pull off the blower and pack it all up to go give a demonstration

Chuck.
 
If I had any type of tool rack on my forge they would still end up on the floor so why bother. I won't mention using an old propane bottle for your forge body.
 
Chuck,

I'm with you here. I actually go about half and half. But I am really talking about welding on only a small pipe to hold a burner, welding on a small shelf in front of the front door, and maybe some angle iron so hard firebricks can be slid in and out as doors. IOW, things that really (for me) increase the utility of the forge, but nothing that would get in the way of a rebuild/portability.

Ray,

Picked one up the other day, but still can't get the valve out:) Anyway, the forges I am building right now need about 18" diameter, so I have to check if I can find a bottle tht big.

Thanks again, and keep em coming,

JOhn
 
John the only purpose of the shell is to hold the refractory or insul wool in position. So thinner is better where weight is a factor.
 
John,

I don't have a door on my forge. I just stack up fire brick in front and us this for any type of shelf I need. If you are making the forge with a door on the front make it from slightly thicker material so welding is easier. You are starting with and 18" dia forge body. How thick are your walls? For my basic welding forge I use a 12" dia forge body and 2" walls giving me an 8" cavity. I have also used 10" dia with 2 inch walls for a 6" cavity. I basically follow Wayne Goddards forge plans. The smaller the cavity the better for me. I make it just large enough to fit the largest box I plan to use.

Chuck
 
Bill,

I'm with you in theory. But I find there are certain things that make my own work much more convenient when permanently fixed to the outside wall of the forge. A pipe to hold my burner, a small rest in front, and maybe some angle to hold hard fire bricks, etc. Right now I have thin, light walls holding my wool and castable in place, but the reduced weight is not worth the trouble of jury rigging external burner holders, work rests, doors, etc.

Chuck,

Sounds good. I am using a vertical forge, so we are talking about slightly different things. I have used Indian George's forges, which seem about like the ones you're describing, but even they have a welded on burner holder. And I like Ron Claiborne's and Darren Ellis' similar designs, which have angle iron for holding hard bricks.

John
 
John,

now I understand, We are talking apples and oranges. I do not use a welded burner on mine. I leave a slight gap and allow the flame to jump across. This prevents burning the end of the burner. This is all referenced to my type of forge. I have used a verticle forge and they do not seem to have as much a problem with this. With all the above said, the basic problem you are having is welding to too thin a material. You should be able to readily weld 1/16th inch material with a wirefeed. Mig is best but flux core will do. Just get the thinnest wire you can and turn down the amperage. I can see there might also be a bit of a problem with sag if the walls are too thin. You may try welding a reenforcing plate to the outside to provide a little more stiffness. I think that 10 ga material would be best for this application. It provides plenty of meat to weld to and is rigid enough to hold up most any attachment. I think you have already found a place to roll you one which is how I get most of my forge bodies. Good luck and get it hot.

Chuck
 
Been welding since the mid 70's,have done code xray work for years.Used some of the most modern equipment there is.I never owned my own welding machine knowing if I ever needed any welding I did it at lunch or after work.A lot of folks looked at me funny when they'd ask about welding something for them after saying I aint got one.I have recently finally got a small AC buzzer but have found that basic red neck coat hanger wire and the oxy/acety torch can do most anything a novice needs including welding handles on billets.Works on thin stuff too.Amazingly strong.
 
Just a note on making BIG forges.If you want 16,18,20,24" diameter,and ease of fitting up the lining and ends - get a 25 to 55 gallon barrel with a removable/replaceable lid. Use the lid for the back end of the forge.Works good horizontal or vertical.I think Don Fogg has a couple of these.
BTW they come in stainless steel ,too.
 
Stacy,

The forge I am replacing is one of these barrel forges. The 55 gal. one works great for heat treating long pieces, because it only needs to get up to 1500 or so. The 18"--while super easy to put together, as you rightly suggest-- I used for damascus is way too thin and weak as temps rise above 2000. The doors are sagging/distorting under the stress of heat and heavy billets, etc.

John
 
Locate one in stainless steel if you can.It might take the higher temps better.I agree that for a high temp forge a beefy shell is a plus.

Here is a tip for those making any forge,but especially good for a barrel forge.

An easy way to insulate the ends is to run a bunch of 1.5" ( if using 2" wool) stainless screws in from the outside.Cut the wool to fit( you can leave it a little oversized for now) and push it on the screws.apply rigidizer to the center area,but not out to the edges (we want them soft for now) and let it dry.Once you have completely finished the inside of the forge lining in the barrel,and let it dry,place plastic wrap (saran) over the edge (so you can remove the end after the rigidized sets up).Test fit the end and trim the wool as needed so it will fit on the barrel and the clamp can be closed.Now put rigidizer on the edge area of the end piece and press it in place,sealing it on with the barrel clamp.Let the rigidizer set up and remove it again.Take off the plastic wrap,finish the insulation on the door with ITC,satanite,whatever, and put it back on,while still wet.It will seal onto the side perfectly. When the ITC/satanite is dry there will be no heat leakage at the joint,and the end/top won't sag so easily under heat.
Use the solid end of the barrel for the door port.
Weld up all the door slides/hinges/etc. before starting the insulation work.The screw trick on the door end of barrel does the same for preventing the insulation from sagging.Of course do all the door and side work before doing the removable end.
Stacy
 
Stacy,

I am having a hard time envisioning your post. OTOH, once I used the Rigidizer I did not need either screws or Satanite (ITC is a different story since it improves insulative qualities). The wool was plenty rigid and plenty stable for all my uses. It never sagged, even in the horizontal 55 gal. barrel, and it appears to be stable in terms of airborne fibers.

John
 
John, what my good buddy Bill meant to say was, "John, my forges are made out of 1/8" thick walled material."

:p :D

I think 1/8" - 3/16" is ideal, as there's enough beef there to weld a heavy shelf in front, burner entry port, and whatever you may want/need to weld to it.

If I didn't care about those things, then a pop can would probably work ;) But I'm like you and want all that stuff welded to my forge body. My adjustable work rest (that Mr. Plain Ol Bill built for me about 5 years ago!) is actually attached to the forge table itself. Much sturdier for holding up heavy stuff in the forge.

I'm in the recycling part of the mill every day at work, and I see all the TONS of black iron and ss pipe and dream of forge building :D :thumbup:

There was a job there when they threw out several BRAND NEW 316L 2" fittings (elbows, straight pieces, reducers, etc.) and it may just happen that they will end up in a future bladesmithing forge! ;)
 
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